HRP940040A2 - Substituted-1,3-oxathiolanes with antiviral properties - Google Patents

Description

This invention relates to new substituted 1,3-oxathiolane cyclic compounds that have pharmacological activity, methods for obtaining these compounds and intermediates, pharmaceutical preparations containing them and the use of these compounds in the antiviral treatment of mammals.

Retroviral infections are serious causes of diseases, most notably acquired immunodeficiency syndrome (AIDS). The human immunodeficiency virus (HIV) is considered to be the etiological agent of AIDS, and compounds possessing an inhibitory effect against the multiplication of HIV are now desired.

Mitsuya et. al., "3'-Azido3'-deoxythymidine (BW A509U): An antiviral agent that inhibits the infectious and cytopathic effects of human T-lymphotropic virus type III/lymphadenophage: bound virus in vitro", Pros.Natl.Acad.Sci.USA. , 82, p. 7096-7100 (1985), designated as a compound of formula (A) (3'-azido-2'3'-dideoxythymidine), commonly designated as AZT. It is thought that this compound may be useful in providing some protection to AIDS carriers from the cytopathogenic, immunosuppressive effects of the virus (HIV).

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Mitsuya et al. "Inhibition of in vitro infectious and cytopathic effects of human T-lymphotropic virus type III/lymphadenopathogen-associated virus (HTLV-III) by 2'3'-dideoxynuleosides", Proc.Natl.Acad.Sci.USA., 86, p. 1911-15 (1986) refers to a group of 2'3'-dideoxynucleotides represented by formula (B) which are said to possess protective activity against HIV-induced cytopathogenicity.

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Balzarini et al. "Strong and selective anti-HTLV-III/LAV activity of 2'3'-dideoxycytidine, a 2'3'-unsaturated derivative of 2'3'-dideoxycytidine", Biochem.Biophys.Res.Comm., 140, p. 735'42 (1986), refers to an unsaturated analogue of these nucleotides-2'3'-dideoxy-cytidine, represented by formula (C), which is characterized by antiretroviral activity.

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Baba et al., "2'3'-dideoxythymidine and its 2'3'-unsaturated derivative (2'3'-dideoxythymidine) are potent selective inhibitors of immunodeficiency virus replication in vitro," Biochem.Biophys.Res.Comm., 142 , p. 128-34 (1987), refers to the 2'3'-unsaturated analogue represented by formula (D) of 2'3'-dideoxythymidine. This analog has been characterized as a strong selective inhibitor of HIV replication.

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Analogues of AZT known as 3'-azido-2'3'-dideoxyuridines represented by formula (E) where Y is bromine or iodo have been reported to possess inhibitory activity against Moloney murine leukemia in T.S. Lin et al., "Syntheses and antiviral activity of various 3'-azido, 3'-amino, 2'3'-unsaturated and 2'3'-dideoxy analogues of pyrimidine deoxoribonucleosides against retroviruses", J.Med.Chem., 30 , p. 440-41 (1987).

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Finally, 3'-fluoro analogs of 2'3'-dideoxycytidine represented by formula G) and 2'3'-dideoxythymidine represented by formula (G) are provided in Herdewijn et al., "3'-Substituted 2'3'-dideoxynucleoside Analogs as potential anti-HIV(HTLV-III/LAV) agents", J.Med.Chem., 30, p. 1270-78 (1987), possess potent antiretroviral activity.

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The most potent anti-HIV compounds listed below are 2'3'-dideoxynuleosides, specifically 2'3'-dideoxy cytidine (ddCyd) and 3'-azido-2'3'-dideoxythymidine (AzddThd or AZT). These compounds are also active against other types of retroviruses such as Moloney murine leukemia virus. Due to the growing prevalence and life-threatening features of AIDS, efforts are directed towards the discovery and development of new non-toxic and potent HIV inhibitors and blockers of its infectivity. Therefore, the object of this invention is to provide effective anti-HIV compounds with low toxicity and the synthesis of such novel compounds which is easily accomplished.

A structurally distinct class of compounds known as 2-substituted-5-substituted-1,3-oxathiolanes has recently been discovered and found to possess antiviral activity.

More specifically, these compounds were found to act as non-toxic inhibitors of HI-1 replication in T-lymphocytes over extended periods of time.

In the first aspect of the invention, compounds of formula (I) are provided

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where R 1 is hydrogen

R2 is a purine pyrimidine base or an analog or derivative thereof;

Z is S, S = O or SO 2 ; and its pharmaceutically acceptable derivatives.

It is clear to those skilled in the art that compounds of formula (I) contain at least two asymmetric centers (shown as * in formula (I) and therefore exist in the form of two pairs of optical isomers (i.e. enantiomers) and mixtures thereof including racemic mixtures. Thus compounds of formula (I) can be either cis isomers, as shown by formula (II), or trans isomers, as shown by formula (III), or mixtures thereof. Each of the cis and trans isomers can exist as one of the two enantiomers or as a mixture thereof including racemic mixtures All such isomers and mixtures thereof, including racemic mixtures, are included in both inventions.

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The compounds of formula (I) are preferably in the form of their cis isomers.

It will also be clear that when Z is S = O the compounds exist in two isomeric forms as shown by formulas (IIa) and (IIb) which differ in the configuration of the oxide oxygen atom in relation to the 2,5-substituents. The compounds of the invention further encompass such isomers and mixtures thereof.

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A purine or pyrimidine base or analog or derivative thereof will have R2 attached at the 9- or 1-position respectively.

Purine or pyrimidine base or analog or its derivative refers to a purine or pyrimidine base found in natural nucleosides or its analog that mimics such bases in structure (types of atoms and their arrangement), are similar to natural bases but may either contain additional or lack functional properties of natural base. Such analogs include those derived by replacing the CH2 group with a nitrogen atom (for example, 5-azapyrimidines such as 5-azacytosine) or vice versa (for example 7-deazapurines, for example 7-deazadenosine or 7-deazaguanosine) or both (i.e. 7 -deaza, 8-azapurines). Derivatives of such bases or analogs are considered those compounds where the ring substituents are either incorporated, or removed or modified by conventional substituents known in the art, eg halogen, hydroxy, C1-6 alkyl. Such purine or pyrimidine bases, analogs and derivatives are known to those skilled in the art.

Usually the R2 group is chosen from:

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wherein R 3 is selected from the group consisting of hydrogen, hydroxymethyl or a saturated C 1-6 alkyl group;

R 4 and R 5 are independently selected from the group consisting of hydrogen, hydroxymethyl, trifluoromethyl, trifluoromethyl, substituted or unsubstituted, saturated or unsaturated C 1-6 alkyl, bromine, chlorine, fluorine or iodine;

R 6 is selected from the group consisting of hydrogen, cyano, carboxy, ethoxycarbonyl, carbamoyl or thiocarbamoyl; and

X and Y are independently selected from the group consisting of hydrogen, bromine, chlorine, fluorine, iodine, amino or hydroxy groups.

R2 is preferred

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where R3 and R4 are as defined above. Z is preferably -S-.

"Pharmaceutically acceptable derivative" means a pharmaceutically acceptable salt, ester or salt of such an ester of a compound of formula (I) or another compound, which, when introduced into a recipient, is capable of giving (directly or indirectly) a compound of formula (I) or an antivirally active metabolite or its residue.

It will be clear to those skilled in the art that the compounds of formula (I) can be modified in order to obtain their pharmaceutically acceptable derivatives, on the functional groups in both base parts, R2 and on the hydroxymethyl group of the oxathiolane ring. Modification of all such functional groups is included within the scope of the invention. However, of particular interest are the pharmaceutically acceptable derivatives (ie esters) obtained by modifying the 2-hydroxymethyl group of the oxathiolane ring.

Preferred esters of compounds of formula (I) include compounds in which R1 is replaced by a carboxyl function R-C in which the non-carbonyl group R of the ester moiety is selected from hydrogen, straight or branched chain alkyl (eg methyl, ethyl, n-propyl, t-butyl, n-butyl), alkoxyalkyl (e.g. methoxymethyl), aralkyl (e.g. benzyl), aryloxyalkyl (e.g. phenoxymethyl), aryl (e.g. phenyl optionally substituted with halogen, C1-4 alkyl or C1-4 alkoxy); substituted dihydro pyridinyl (eg N-methyldihydro pyridinyl); sulfonate esters such as alkyl or aralkylsulfonyl (eg methanesulfonyl): sulfate esters: esters of amino acids (eg L-valyl or L-isoleucyl) and mono-di- or tri-phosphate esters.

Also included in the scope of the invention are such esters and esters derived from polyfunctional acids such as carboxylic acids containing more than one carboxylic group, for example, dicarboxylic acids HO2C (CH2)nCO2H where the integer is from 1 to 10 (eg succinic acid ) or phosphoric acid. Processes for obtaining such esters are well known. See, for example, Hahn et al. "Nucleotide dimers as anti-human immunosuppressive viral agents", Nucleotide Analogeus p. 156-159 (1989) and Busso et al., "Nucleotide Dimeric Suppressors of HIV Expression in Vitro", AIDS Research and Human Retroviruses, 4 (6) p. 449-455 (1988). When esters are derived from such acids, each acid group is preferably esterified with a compound of formula (I) or other nucleosides or analogs and their derivatives to obtain esters of formula (IV).

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and n is an integer from 1 to 10 or

J is a nucleoside or nucleoside analog or derivative thereof and Z and R 2 have the above meanings. Among the preferred nucleosides and nucleoside analogs are 3' -azido-2' 3' -dideoxythymidine, 2' 3' -dideoxycytidine, 2' 3' -dideoxyadenosine, 2' 3' -dideoxoinosine, 2'3'-dideoxythymidine, 2'3' '-dideoxy-2'3'-didehydro-thymidine and 2'3'-dideoxy-2'3'-didehydroxycytidine and ribavirin and those nucleosides whose bases are listed on pages 7-8 of this specification. For us, the most preferred homodimer is composed of two nucleotides of formula (I). For us, the most preferred homodimer is composed of two nucleotides of formula (I). With regard to the esters described above, unless otherwise indicated, any alkyl group containing 1 to 16 carbon atoms, preferably 1 to 4 carbon atoms and may contain one or more double bonds, is suitable. The aryl group present in such esters conveniently includes a phenyl group. More specifically, esters can be C1-16 alkyl esters, unsubstituted benzoyl ester or benzoyl ester substituted with at least one halogen (bromine, chlorine, fluorine or iodine), saturated or unsaturated C1-6 alkoxy, nitro or trifluoromethyl groups.

Pharmaceutically acceptable salts of the compounds of formula (I) include those derived from pharmaceutically acceptable inorganic and organic acids and bases. Examples of suitable acids include hydrochloric, hydrobromic, nitric, perchloric, fumaric, maleic, phosphoric, glycolic, lactic, salicylic, succinic, toluene-p-sulfonic, tartaric, acetic, citric, methanesulfonic, formic, benzoic, malonic, naphthalene-2- sulfonic and benzenesulfonic acid. Other acids such as oxalic, which are not pharmaceutically acceptable by themselves, can be used to obtain salts applicable as intermediates in obtaining the compounds of the invention and their pharmaceutically acceptable additive salts with acids.

Salts derived from appropriate bases include alkali metal (eg sodium), alkaline earth metal (eg magnesium) ammonium and NR 4 + (where R is C 1-4 alkyl) salts.

Further references to the compound according to the invention include both compounds of formula (I) and their pharmaceutically acceptable derivatives.

Specific compounds of formula (I) include:

Cis-2-hydroxymethyl-5-(cytosin-1'-yl)-1,3-oxathiolane, trans-2-hydroxymethyl-5-(cytosin-1'-yl)-1,3-oxational, and their

mixtures;

Cis-2-benzoyloxymethyl-5-(cytosin-1'-yl)-1,3-oxathiolane, trans-2-benzoyloxymethyl-5-(cytosin-1'-yl)-1,3-oxathiolane and their

mixtures;

Cis-2-hydroxymethyl-5-(N'4-acetyl-cytosin-1'-yl)-1,3-oxathiolane, trans-2-hydroxymethyl-5-(N'4-acetyl-cytosin-1'-yl) )-1,3-

oxathiolane and their mixtures;

Cis-2-benzoyloxymethyl-5-(N'4-acetyl-cytosin-1'-yl)-1,3-oxathiolane, trans-2-benzoylmethyl-5-(N'4-acetyl-cytosin-1'-yl) )-1,3-

oxathiolane and their mixtures;

Cis-2-hydroxymethyl-5-(cytosin-1'-yl)-3-oxo-1,3-oxathiolane;

Cis-2-hydroxymethyl-5-(N-dimethylamino-methylene cytosin-1'-yl)-1,3-oxathiolane;

Bis-Cis-2-succinyloxymethyl-5-(cytosine-1')-1,3-oxathiolane;

Cis-2-benzoyloxymethyl-5-(6'-chloropurin-N-9'-yl)-1,3-oxathiolane; trans-2-benzoyloxymethyl-5-(6'-chloropurin-N-9'-yl)-1,3-

oxathiolane, and their mixtures;

Cis-2-hydroxymethyl-5-(6'-hydroxypurin-N-9'-yl)-1,3-oxathiolane;

Cis-2-benzoyloxymethyl-5-(uracil-N-1'-yl)-1,3oxathiolane, trans-2-benzoyloxymethyl-5-(uracil-N-1'-yl)-1,3-oxathiolane, and

mixtures thereof;

Cis-2-hydroxymethyl-5-(uracil-N-1'-yl)-1,3-oxathiolane;

Cis-2-benzoyloxymethyl-5-(thymin-N-1'-yl)-1,3oxathiolane, trans-2-benzoyloxymethyl-5-(thymin-N-1'-yl)-1,3-oxathiolane, and

mixtures thereof;

Cis-2-hydroxymethyl-5-(thymin-N-1'-yl)-1,3-oxathiolane. In the form of a racemic mixture or as individual enantiomers.

The compounds of the invention themselves possess antiviral activity and/or are metabolized to such compounds. Specifically, these compounds are effective in inhibiting the replication of retroviruses, including human retroviruses such as human immunodeficiency viruses (HIVs), the agents that cause AIDS.

Thus, as a further aspect of the invention, a compound of formula (I) or a pharmaceutically acceptable derivative thereof is provided for use as an active therapeutic agent, more precisely as an antiviral agent, for example for the treatment of retroviral infections.

In a further alternative aspect, a method for treating a viral infection, more specifically an infection caused by a retrovirus such as HIV in mammals, including humans, is provided, which comprises introducing into the body an effective amount of an antiviral compound of formula (I) or a pharmaceutically acceptable derivative thereof.

Also, in a further alternative aspect of this invention, the use of the compound of formula (I) or its pharmaceutically acceptable derivative for the production of a drug for the treatment of a viral infection is provided.

The compounds of the invention are also applicable in the treatment of AIDS-related conditions, such as AIDS-related complex (ARC), persistent generalized lymphadenopathy (PGL), AIDS-related neurological conditions (such as dementia), anti-HIV antibody positive and HIV-positive conditions, Kaposi's sarcoma, thrombocytopenic spot and occasional infections.

The compounds of the invention are also applicable in the prevention or progression of clinical disease in individuals who are anti-HIV antibody or HIV-antigen positive or in prophylaxis due to exposure to HIV.

The compounds of formula (I) or their pharmaceutically acceptable derivatives can also be used to prevent viral contamination of biological fluids such as blood or semen in vitro.

Some compounds of formula (I) are also applicable as intermediates in the preparation of other compounds of the invention.

It will be clear to those skilled in the art that the treatment information provided here applies to both prophylaxis and treatment of established infections or symptoms.

Furthermore, it will be clear that the amount of compounds of the invention required for use in the treatment will vary not only with the particular compound chosen but also depending on the method of introduction into the body, the nature of the condition being treated and the age and condition of the patient and is solely within the competence of the physician or veterinarian. . In general, however, a suitable dosage will be in the range of about 1 to about 750 mg/kg of body weight per day, such as 3 to about 120 mg per kilogram of body weight of the recipient per day, preferably in the range of 6 to 90 mg/kg/day, most preferably in the range of 15 to 60 mg/kg/day.

The desired dose may usually be present in a single dose or as divided doses administered at appropriate intervals, four or more sub-doses per day.

The compound is usually administered as a unit dose; for example those containing 10 to 1500 mg, usually 20 to 1000 mg, most commonly 50 to 700 mg of active ingredient per unit dose.

Ideally, the active ingredient should be administered so as to reach a maximum plasma concentration of the active compound of about 1 to 75 μM, preferably about 2 to 50 μM, most preferably about 3 to about 30 μM. This can be achieved, for example, by intravenous injections of a 0.1 to 5% solution of the active ingredient, optionally in saline, or large pills containing about 0.1 to about 110 mg/kg of the active ingredient. Desired blood levels can be maintained by continuous infusion to provide about 0.01 to about 5.0 mg/kg/hour or by intermittent infusions containing about 0.4 to about 15 mg/kg of active ingredient.

When possible, for use in therapy, the compound of the invention can be introduced into the organism as a raw chemical, although it is preferable to introduce it as the active ingredient present in the pharmaceutical formulation.

The invention further provides a pharmaceutical formulation comprising a compound of formula (I) or a pharmaceutically acceptable derivative thereof together with one or more pharmaceutically acceptable carriers and optionally together with other therapeutic and/or prophylactic ingredients. The carrier(s) must be "acceptable" in the sense that it is compatible with the other ingredients of the formulation and does not harm the recipient.

Pharmaceutical formulations include those suitable for oral, rectal, nasal, topical (including oral and sublingual), vaginal, parenteral (including intramuscular, subcutaneous and intravenous) administration or a form suitable for administration by inhalation or inhalation. The formulations may, where appropriate, be conveniently presented in unit doses and may be prepared by any of the procedures well known in pharmacy. All processes include the step of bringing the active compound into contact with liquid or finely divided solid carriers, or both, and then, if necessary, molding the product into the desired formulation.

Pharmaceutical formulations suitable for oral administration may typically be present as individual units such as capsules, pills or tablets each containing a predetermined amount of active ingredient; as powder or granules; as a solution; as a suspension; or as an emulsion. The active ingredient may also be present as a large tablet, electuary or paste. Tablets and capsules for oral administration may contain common additives such as binding agents, fillers, lubricants, disintegrants or wetting agents. Tablets can be coated according to any of the well-known methods. Liquid oral preparations may be in the form of, for example, aqueous or oily suspensions, solutions, emulsions, syrups or elixirs, or dry products may be present for mixing with water or other suitable vehicle prior to use. Such liquid preparations may contain conventional additives such as suspending agents, emulsifying agents, non-aqueous carriers (which may include edible oils) or preservatives.

The compounds of the invention may also be formulated for parenteral administration (e.g. by injection, for example by bulk injection or continuous infusion) and may be present in unit dose form in ampoules, pre-filled syringes, low volume infusion or multi-dose containers to which a preservative has been added. . The preparations may be taken in forms such as suspensions, solutions or emulsions in oily or aqueous carriers and may contain formulating agents such as suspending, stabilizing and/or dispersing agents. Alternatively, the active ingredient can be in powder form, obtained by aseptic isolation of a sterile solid substance or lyophilization from a solution for constitution with a suitable carrier, eg sterile water without combustible ingredients, before use.

For topical application to the epidermis, the compounds of the invention may be formulated as ointments, creams or lotions, or as coated patches. Ointments and creams may, for example, be formulated with a water or oil base with the addition of suitable thickening and/or gelling agents. Lotions may be formulated with an aqueous or oil base and will generally also contain one or more emulsifying, stabilizing, dispersing, suspending, thickening or coloring agents.

Formulations suitable for topical oral administration include pills containing the active ingredient in a flavored base, usually sucrose and gum acacia or tragacanth; pills contain the active ingredient in an inert base such as gelatin and glycerin or sucrose and acacia; mouthwashes comprise the active ingredient in a suitable liquid carrier.

Pharmaceutical formulations suitable for rectal administration where the carrier is a solid substance are most preferably presented as a suppository unit dose. Suitable carriers include cocoa butter and other materials commonly used in pharmacy and suppositories may be commonly made by mixing the active compound with softened molten carriers, then cooled and molded.

Formulations suitable for vaginal administration may be present as pessaries, tampons, creams, gels, ointments, foams or sprays containing, in addition to the active ingredient, carriers well known in pharmacy.

For intra-nasal administration, the invention can be used as a liquid spray or dispersible powder or in the form of drops.

Drops may be formulated with an aqueous or non-aqueous base that also contains one or more dispersing, dissolving or suspending agents. Liquid sprays are usually supplied in pressurized packages.

For administration by inhalation, the compounds of the invention are used from insufflation, nebulization, or pressurized packaging or other conventional aerosol spray delivery methods. Pressurized packages may contain a suitable propellant such as dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, carbon dioxide or other suitable gas. In the case of pressurized aerosols, the unit dose may be determined by providing a metered dose valve.

Alternatively, for inhalation or inhalation, the compounds of the invention may be taken in dry powder form, for example a powder mixture of the compound and a suitable base powder such as lactose or starch. The preparation in the form of powder may be present in the form of a unit dose, for example as capsules or pods or for example gelatin or blister packages from which the powder can be introduced into the body by means of an inhaler or a puffer.

When desired, the above-described formulations adapted to provide sustained release of the active ingredient can be used.

Pharmaceutical preparations according to the invention may also contain other active ingredients such as antimicrobial agents or preservatives.

The compounds of the invention may also be used in combination with other therapeutic agents, for example, other anti-infective agents.

Thus, the invention further provides a combination comprising a compound of formula (I) or a physiologically acceptable derivative thereof together with another therapeutically active agent, more precisely, an antiviral agent.

The combinations set forth above may be commonly present for use in the form of a pharmaceutical formulation and such pharmaceutical formulations comprising a combination as defined above together with a pharmaceutically acceptable carrier form a further aspect of the invention.

Suitable therapeutic agents for use in such combinations include acyclic nucleotides such as acyclovir, ganciclovir, interferons such as alpha-, beta-, and gamma-interferon; glucurglucoronation inhibitors such as probenecid; nucleoside transport inhibitors such as dipyridamole analogs; nucleoside analogs such as 3'-azido-2', 3'-dideoxythymidine, 2'3'-dideoxycytidine, 2'3'-dideoxyadenosine, 2'3'-dideoxyinosine, 2'3'-dideoxythymidine, 2'3' -dideoxy, 2'3'-didehydrothymidine and 2'3'-dideoxy-2'3'-didehydrocytidine and ribavirin; immunomodulators such as interleukin II (IL2) and granulocyte colony-stimulating factor, macrophages (GM-CSF), erythropoietin, ampligen, thymomodulin, thymopentin, foscarnet, glycosylation inhibitors such as 2-deoxy-D-glucose, castanospermine, 1-deoxynozirimycin; and HIV inhibitors that bind to CD4 receptors such as soluble CD4, CD4 fragments and CD4-hybrid molecules.

The individual components of such combinations may be administered either subsequently or simultaneously in separate or combined pharmaceutical formulations.

When a compound of formula (I) or a pharmaceutically acceptable derivative thereof is used in combination with another therapeutic agent active against the same virus, the dose of each compound must be either the same or different from that when the compound is used alone. The appropriate dosage will be readily recognized by those skilled in the art.

Compounds of formula (I) and their pharmaceutically acceptable derivatives can be obtained by some of the known methods for obtaining compounds of analogous structure.

R 1 and R 2 as used in the text below, have the same meaning as defined above, unless otherwise indicated.

In one such process (A), 1,3-oxathiolane of formula (VIII)

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where R 1 is hydrogen or a hydroxy protecting group as defined and the anomeric group L is a group or atom which is substituted and reacted with the appropriate base. Suitable groups include alkoxy carbonyl groups such as ethoxy carbonyl or halogens, for example, iodo, bromo, or chlorine or -OR where R is a substituted or unsubstituted, saturated or unsaturated alkyl group, e.g. a C1-6 alkyl group such as methyl or is R is a substituted or unsubstituted, aliphatic or aromatic acyl group, eg a C1-6 aliphatic acyl group such as acetyl, and an aromatic acyl group such as benzoyl.

A compound of formula VIII is usually reacted with the appropriate purine or pyrimidine base R2-H (previously silylated with a silating agent such as hexamethyldisilazine) in a compatible solvent such as methylene chloride using a Lewis acid (such as titanium tetrachloride or stannous chloride) or trimethylsilytriflate.

1,2-oxathiolanes of formula (VIII) can be obtained, for example, by reacting an aldehyde of formula (II) with a mercaptoacetal of formula (VI) in a compatible organic solvent, such as toluene, in the presence of an acidic catalyst such as para-toluene sulfonic acid or A Lewis acid, eg zinc chloride.

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Mercaptoacetals of formula (VI) can be obtained by known methods, for example, G. Hesse and I. Jorder, "Mercaptoacetaldehyde and 1,4-dithiane", Chem. Ber. 85. p. 924-932, (1952).

Aldehydes of formula (VII) can be obtained by known procedures, for example, E.G. Hallquist and H.Hibbert, "Reaction Investigations Related to Carbohydrates and Polysaccharides, Part XLIV: Synthesis of Isomeric Bicyclic Acetal Ethers", Can.J.Research, 8, p. 129-136 (1933).

In the second process (B), one of the compounds of formula (I) is converted into another compound of formula (I) by base interconversion. Such interconversion can be performed either by simple chemical transformation (eg, converting a uracil base to cytosine) or by enzymatic displacement using, for example, deoxyribosyl transferase. Such procedures and conditions for base interconversion are well known in nucleoside chemistry.

In the third process (C), the compounds of the formula (B) can be obtained by the reaction of the compound of the formula

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with the compound formula

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where P is a protecting group, and then removing the protecting group.

Compounds of formula (IX) can be obtained by the reaction of a suitable epoxide (XI)

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with a suitable sulfur-containing compound, for example, sodium thioacetate. Compounds of formula (I) are known or can be obtained by analogous procedures.

In the fourth procedure (D), the compound of formula (XII)

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can be converted into a compound of formula (I) by converting the anomeric NH2 group into the required base by procedures known in nucleoside chemistry.

Many of the reactions described above have been widely described in connection with purine nucleoside syntheses, for example, in "Nucleoside Analogues - Chemistry, Biology and Medical Applications", R.T. Walker et al., Ed. Plenum Press, New York (1979, at pp. 193-223, text incorporated herein.

It will be appreciated that the above reactions may require the use of, or commonly employ, starting materials having protected functional groups, and deprotection may be required as an intermediate or final step to obtain the desired compound. Protection and deprotection of functional groups can be performed using conventional means. Thus, for example, amino groups may be protected by a group selected from aralkyl (eg benzyl), acyl or aryl (eg 2,4-dinitrophenyl) groups; then deprotection is performed when desired by hydrolysis or hydrogenolysis using appropriate standard conditions. Hydroxyl groups can be protected using conventional hydroxy protecting groups, for example, as described in "Protecting Groups in Organic Chemistry" ed. J.F.W. McOmie (Plenum Press, 1973) or "Protecting Groups in Organic Synthesis" by Theodore W. Greene (John Wiley & Sons, 1981). Examples of suitable hydroxy-protecting groups include groups selected from alkyl (eg methyl, t-butyl or methoxymethyl), aralkyl (eg benzyl, diphenylmethyl or triphenylmethyl), heterocyclic groups such as tetrahydropyranyl, acyl (eg acetyl or benzyl) and silyl groups as trialkylsilyl (eg, t-butyldimethylsilyl). Hydroxy-protecting groups can be removed using conventional techniques. Thus, for example, alkyl, silyl, acyl and heterocyclic groups can be removed by solvolysis, eg, hydrolysis in a basic or acidic medium. Aralkyl groups such as triphenylmethyl groups can similarly be removed by solvolysis, e.g., hydrolysis in an acidic medium. Aralkyl groups such as benzyl can be cleaved, for example, by treatment with BF 3 /etherate and acetic anhydride and then removal of the acetate groups thus awarded at the appropriate step of the synthesis. Silyl groups can also be conventionally removed using a fluoride ion source such as tetra-n-butylammonium fluoride.

In the above procedures, compounds of formula (I) are usually obtained as a mixture of cis and trans isomers.

These isomers can be separated, for example, by acylation, eg with acetic anhydride and then separation by physical procedures, eg silica gel chromatography and deacetylation, eg with methanolic ammonia or fractional crystallization.

Pharmaceutically acceptable salts of the compounds of the invention can be prepared as described in US Pat. 4.3383.114, the disclosure of which is incorporated herein by reference. Thus, for example, when it is desired to obtain an additive salt of a compound of formula (I) with an acid, the product of the above procedures can be converted into a salt by treating the resulting free base with a suitable acid using conventional procedures. Pharmaceutically acceptable acid addition salts can be prepared by reacting the free base with the appropriate acid of choice in the presence of a suitable solvent such as an ester (eg, ethyl acetate) or an alcohol (eg, methanol, ethanol, or isopropanol). Inorganic base salts can be prepared by reacting the free base with a suitable base such as an alkoxide (eg sodium methoxide) optionally in the presence of a solvent such as an alcohol (eg methanol); pharmaceutically acceptable salts may also be obtained from other salts, including other pharmaceutically acceptable salts of compounds of formula (I) using conventional procedures. A compound of formula (I) may be converted to a pharmaceutically acceptable phosphate or other ester by reaction with a phosphorylating agent such as POCl 3 or a suitable esterifying agent such as halide acid or an anhydride as appropriate. The ester or salt of the compound of formula (I) can be converted into the starting compound, for example by hydrolysis.

If the compound of formula (I) is desired as a single isomer, this can be obtained by decomposition of the final product or by stereospecific syntheses from isomerically pure starting materials or a suitable intermediate.

Decomposition of the final product, or intermediate, or starting material may be carried out by any suitable known procedure: see for example, Stereochemistry of Carbon Compounds. by E.L. Eliel (McGraw Hill, 1962) and Tables of Decomposing Agents by S.H. Wilen.

The invention will be further described by the following examples which are not intended to limit the invention in any way. All temperatures are in degrees Celsius.

Examples

Example 1

2-thiobenzoyl acetaldehyde diethyl acetal

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To a solution of potassium t-butoxide (11.5 g, 0.11 mol) in DMF (100 ml) was added thiobenzic acid (17 g, 0.11 mol) and the solution was partially evaporated under vacuum, two portions of benzene were successively added , which was each time accompanied by vacuum evaporation. Bromoacetaldehyde diethylacetal (20.3 g, 0.1 mol) was added to the remaining DMF solution and the mixture was stirred for 15 hours at 120°C. After cooling, the mixture was poured into water (500 ml) and the product was extracted with ether (3 x 200 ml), the extract was washed with aqueous NaHCO3 solution and then with water after which it was dried and the solvent was removed in vacuo. The residue was distilled in vacuo to give 17.2 g of pure compound (V), mp 131-133°C/0.07 mm It was characterized by 1H NMR δ (ppm, CDCl3):

7.97 (d, 2H; aromatic)

7.47 (m, 3H; aromatic)

4.59 (t, 1H; -CH; (OC2H5)2)

3.66 (m, 4H; 2 x OCH2CH3)

3.30 (d, 2H; SCH2-)

1.23 (t, 6H; 2 x OCH2CH3)

Example 2

Mercanpoacetaldehyde diethylacetal

[image]

The previously obtained thiobenzoyl derivative of formula (V) (17.2 g) was dissolved in 100 ml of THF, which was further accompanied by the addition of 6 g of NaOH in 20 ml of H2O. The mixture was refluxed under N 2 for 15 h, then cooled and diluted with water (200 mL; and the product was extracted with ether (3 x 200 mL). The extract was dried, the solvent was removed in vacuo and the residue was distilled in vacuo to give 7 ,1 g of pure compound of formula (VI), mp 60-62oC/18mm.The product was characterized by 1H NMR δ (ppm, CDCl3):

4.51 (t,1H; CH(OC2H5)2)

3.51 (m, 4H; 2 x OCH2CH3)

2.65 (dd, 2H; HS-Ch2)

1.54 (t,1H; HS-).

1.23 (t, 6H; 2 x OCH2CH3)

Example 3

Benzoyloxyacetaldehyde

[image]

This known intermediate was obtained by a process not previously described from the known 1-benzoyl glycerol. Thus, 50 g of the latter in a mixture of 500 ml of CH2Cl2 and 25 ml of H2O was treated in portions with 80 g of NaJO4 with vigorous stirring at room temperature. After the addition, stirring was continued for 2 hours after which 100 g of MgSO4 was added and stirring was continued for another 30 minutes. The mixture was filtered, the filtrate was evaporated under vacuum and the residue was predistilled under vacuum to obtain 26g of pure compound of formula (VII) b.p. 92-94°C/0.25 mm. 1H NMR (200 MH2; CDCl3, TMS as internal reference); δ (ppm):

9.71 (s, 1H;-CHO);

8.11 (d, H; aromatic)

7.60 (m, 1H; aromatic)

7.46 (m, 2H; aromatic)

4.88 (s, 2H; -CH 2 CHO).

Example 4

2-benzoyloxymethyl-5-ethoxy-1 3-oxathiolane

[image]

The previous mercaptoacetaldehyde acetal of formula (VI) (7 g) was mixed in 100 ml of toluene with 7 g of the above benzoyloxyacetaldehyde of formula (VII), a few crystals of p.toluenesulfonic acid were added and the mixture was placed in an oil bath at 120°C under N2. The resulting ethanol was allowed to distill off, the mixture was kept for another 30 minutes at 120°C longer than it was cooled and was washed with an aqueous solution of NaHCO3, dried and evaporated under vacuum.

The residue was predistilled under vacuum to obtain 9.8 g of the pure compound of formula (XIII) as a mixture of cis- and trans-isomers, b.p.

140-143°C/0.1 mm; Rf 0.51 (hexane-EtOAc); δ (ppm, CDCl3);

8.05 (m, 2H; aromatic)

7.57 (m, 1H; aromatic)

7.43 (m, 2H; aromatic)

5.55 (m, 2H; C5-H, C2-H)

4.55 (m, 2H; C2-C5HCO2CH2)

3.80 (m, 1H; C5-C6H5CO2CH2)

[image]

Example 5

Cis- and trans-2-benzoyloxymethyl-5-cytosin-1'-yl-1,3-oxathiolanes

[image]

A mixture of 2.7 g of cytosine, 30 ml of hexamethyldisilazane (HMDS) and 0.3 ml of trimethylsilyl chloride (TMSCl) was heated under reflux under dry N2 until a clear solution was obtained (3 hours) and the excess reagent was evaporated under vacuum. The remaining volatile part was removed under high vacuum (15 min.), the remaining solid substance was introduced into 250 ml of 1,2-dichloroethane and 5 g of the above key intermediate of formula (XIII) in 50 ml of dichloroethane was added to the mixture under dry argon, and then 4.7 ml of trimethylsilyl triflate (TMSTf) was also added.

After three days of heating under reflux under argon, the mixture was cooled and poured into 300 ml of saturated aqueous NaHCO3 solution. The organic layer was collected, the aqueous phase was extracted with CH2Cl2 (2 x 100 ml) and the combined extracts were washed with water, dried and evaporated under vacuum. The residue was purified by chromatography on silica gel using CH2Cl2:CH3OH 9:1 as eluent to give 2.5 g of a pure mixture of cis- and trans(XIV) in a 1:1 ratio as indicated by 1 HNMR. These were resolved as N-acetyl derivatives as described in the following example.

Example 6

Cis- and trans-isomers 2-benzoyloxymethyl-5-(N'-acetyl-cytosine 1'-yl)-1,3-oxathiolane

[image]

The previous mixture of formula (XIV) (2.5 g) in 100 ml of dry pyridine containing 0.1 g of 4-dimethylaminopyridine (DMAP) was treated with acetic anhydride (7 ml) at room temperature and after 16 hours the mixture was poured into a cold water and then extracted with CH2Cl3 (3 x 150 ml). The extract was washed with water, dried and evaporated under vacuum. Toluene was added to the residue and evaporated in vacuo and the remaining oil was purified by chromatography on silica gel using EtOAc :CH3OH 99:1 as eluent to give 1.35 g of pure trans-(XV) as a fast moving product and 1.20 g of pure cis - (XV) as a slow moving component. Both were characterized by 1H NMR spectroscopy.

trans- (XV) : t.klj. 158-160°C; Rf: 0.48 EtOAc:CH3OH 95:5 U.V. (CH3OH) Lambda max: 297 nm

δ (ppm, CDCl13) :

9.00 (b,1H;C4'-NH-Ac)

8.06 (m,2H; aromatic)

7.74 (d.1H; C6'-h)

7.56 (m, 1H; aromatic)

7.47 (d, 1H; C5'-H);

7.45 (m, 2H ; aromatic)

6.53 (dd, 1H; C5-H)

5.89 (dd, 1H; C2-H)

4.46 (dd, 2H; C2-CH2OCOC6H5)

3.66 (dd, 1H; C4-H)

3.32 (dd, 1H; C1-H)

2.25 (s, 3H; NH-COCH3).

Cis-(XV):t.klj. 150-152° Rf: 0.40 EtOAc:MeOH 95:5)

U.V.: (CH3OH) Lambda max 297 nm 1H NMR

δ (ppm, CDCl3):

9.03 (b, 1H; NH-Ac)

8.21 (d, 1H; C6'-H)

8.05 (m, 2H; aromatic)

7.60 (m, 1H; aromatic)

7.50 (m, 2H; aromatic)

7.29 (d, 1H; C5'-h);

6.34 (dd, 1H; C5-H);

5.52 (dd. 1H; C2-H);

4.80 (dd, 2H;C2-CH2OCOC6H5)

3.66 (dd, 1H; C4-H)

3.24 (dd, 1H; C4-H)

2.23 (s, 3H; NH-COCH3).

Example 7

Cis- and trans-2-hydroxymethyl-5-(cytosin-1'-yl)-1,3-oxathiolanes

[image]

a) Trans-(XVI): 375 mg of the previous trans-(XV) was dissolved in 100 ml of methanolic ammonia at 24°C and after stirring for 16 hours, the solution was placed under vacuum and the residue was crystallized from ether. Recrystallization from ethanol-ether gave 174 mg of pure product, m.p. above 220°C (different). It was characterized by 1H and 13C NMR.

1H NMR δ (ppm, DMSO-d6):

7.57 (d, 1H; C6'-H)

7.18 (d, 2H; C4'-NH2)

6.30 (dd, 1H; C5'-H)

5.68 (d, 1H; C5'-h)

5.48 (t, 1H; C2-H)

5.18 (t, 1H; C2-CH2OH)

3.45 (m, 3H; C2-CH2OH + C4H)

3.06 (dd, 1H; C4-H).

U.V.: (CH3OH) Lambda max: 270 nm

13C NMR (DMSO-d6, Varian XL-300); δ in ppm:

C2' C4' C5' C6' C5 C4 C2 CH2OH

154.71 165.70 93.47 140.95 87.77 36.14 86.80 64.71

b) Cis-(XVI): treatment of 375 mg of cis-(XV) by the previous procedure gives 165 mg of pure product after recrystallization from ethanol-ether, m.p. 171-173°C. It was characterized by 1H and 13C NMR.

1H NMR: δ (ppm, DMSO-d6):

7.80 (d, 1H; C6')

7.20 (d, 2H; C4'-NH2)

6.18 (t, 1H; C5-H)

5.14 (t, 1H; C2-CH2O)

3.71 (m, 2H; C2-CH2OH)

3.40 (dd, 1H; C4-H)

2.99 (dd, 1H; C4-H)

U.V.: (CH3OH) Lambda max : 270 nm 13C NMR δ (ppm in DMSO-d6)

C2' C4' C5' C6' C5 C4 C2 CH2OH

154.63 165.59 93.86 140.91 86.47 36.22 85.75 62.79

Example 8

Cis-2-hydroxymethyl-5-(cytosin-1'-yl)-3-oxo-1,3-oxathiolane

[image]

The previous cis- (XVI) (100 mg) in 30 ml of ice-cooled methanol was treated with 93 mg of meta-chloro-perbenzoic acid and after stirring for 15 min a white solid separated which was collected and washed with 10 ml of methanol to obtain 45 mg of pure sulfoxide isomer. The methanol filtrates were evaporated under vacuum and the solid residue was washed with 15 ml of ethanolether (1:1) and then with 30 ml of ether to give 50 mg of pure sulfoxide isomer b. The isomers were characterized by 1H NMR.

Isomer (XVII))a: m.p. above 270°C (different) ; Rf 0.30 (CH2 Cl2 - MeOH 3:1) In .v.:

(CH3OH) Lambda max 270 nm.

δ (ppm, DMSO-d6):

7.68 (d, 1H; C6'-H)

7.36 (s, 2H; C4'-NH2)

6.69 (dd, 1H; C5-H)

5.76 (d, 1H; C5'-H)

5.47 (t, 1H; C2-CH2OH)

4.63 (dd 1H; C2-H)

3.88 (m, 1H; C2-CH-OH)

H

3.72 (m, 1H; C2-CH-OH)

H

3.36 (dd, 1H; C4-H)

3.05 (dd, 1H; C4-H)

Isomer (XVII): m.p. >220' (distance); Rf: 0.32 CH2Cl2:MeOH 3:1

δ (ppm, DMSO-d6):

7.76 (d, 1H; C6'-H);

7.28 (d, 2H; C4'-NH2)

6.66 (dd, 1H; C5-H);

5.77 (d, 1H; C5'-H);

5.45 (t, 1H; C2-CH2OH);

4.64 (t, 1H; C2-H);

3.77 (t, 2H; C2-CH2OH)

3.65 (dd, 1H; C4-H).

3.17 (dd, 1H; C4-H).

Example 9

Cis-2-hydroxymethyl-5-(N-dimethylamino methylene cytosin-1'-yl) 1,3-oxathiolane

[image]

300 mg of cis-2-hydroxymethyl-5-(cytosin-1'-yl)-1,3-oxathiolane was suspended in 10 ml of N-dimethyl acetal (DMF-dimethyl acetal). The mixture was stirred overnight at room temperature (18 hours). Volatile matter was removed by evaporation under reduced pressure. The residue was crystallized from ethanol-ether. 345 mg (93%) of pure product was obtained.

d.p. 162-164°C : Rf: 0.56 in CH2Cl2MeOH 4:1

U.V.: Lambda max: 325 nm 1H-NMR: δ (ppm in DMSO-d6)

8.64 (s, 1H, N=CH-N)

8.04 (d, 1H, C6'-H, J - 7.2 Hz)

6.22 (t, H, C5-H, J = 4.9 Hz)

5.97 (d, 1H, C5'-h, J = 7.2 Hz)

5.37 (t, 1H, -OH, J = 5.8 Hz, D2O exchange)

5.22 (t, 1H, C2-H, J = 4.4 Hz)

3.77 (t, 2H, C2-CH2OH, J - 4.9 Hz)

3.50 (dd, 1H, C4-H, J = 4.9 and 9.9 Hz)

3.17 (s, 3H, -CH3)

3.12 (dd, 1H, C4-H, J = 4.2 and 11.9Hz)

3.04 (s, 3H, -CH3)

Example 10

Bis-Cis-2-succinyloxymethyl-5-(cytosin-1'-yl)-1,3-oxathiolane

[image]

284 mg of cis-2-hydroxymethyl-5-(NN,N-dimethylamino methylene cytosin-1'-yl)-1,3-oxathiolane was dissolved in 10 ml of dry pyridine and cooled to 0°C in an ice bath. 60.1 succinyl chloride was added with a syringe. The mixture was stirred overnight (18 hours) and poured into 50 ml of saturated aqueous NaHCO3 solution. The mixture was extracted with methylene chloride (3x50 ml). The combined CH 2 Cl 2 solution was washed with water (2x50 ml) and dried over MgSO 4 . After filtration, the solvent was removed by evaporation under reduced pressure. The foamy residue was dissolved in 10 ml of CH2Cl2, containing 5 ml of methanol. 80% aqueous acetic acid was added to the mixture and the mixture was stirred overnight at room temperature. The mixture was evaporated to dryness. The solid residue was purified on silica gel using CH2Cl2:MeOH 4:1 as eluant. 145 mg (54%) of pure product was obtained. Decomposes above 230°C; Rf: 0.23 in CH2Cl2:MeOH 4:1

U.V. : ( MeOH ) Lambda max : 271 nm 1H-NMR: δ (ppm in DMSO-d6)

7.69 (d, 2H, 2 x C6'-H, J = 7.6 Hz

7.28 (d, 4H, 2 x NH2, J = 24.9 Hz, D2O exchange)

6.24 (t, 2H, 2 x C5-H, J = 5.6 Hz)

5.76 (d, 2H, 2 x C5'-H, J = 7.4 Hz)

5.35 (t, 2H, 2 x C2-H, J = 4.5 Hz)

4.37 (d, 4H, 2 x C2-CH2O-)

3.42 (dd, 2H, 2 x C4-H, J - 5.5 and 10.9 Hz)

3.10(dd, 2H, 2 x C4-H, J = 5.6 and 11.7Hz)

2.60 (s, 4H, 2 x -CH2-C-O)

Example 11

Cis- and trans-2-benzoyloxymethyl-5-(6'chloropurin-N-9'-yl)1,3-oxathiolanes

[image]

1.7 g of 6-chloropurine was heated at reflux in 50 ml of HMDS (hexamethyldisilazane) containing 50 mg of (NH4)2SO4 (ammonium sulfate) until the solution became clear (1 hour). The oily residue was dried under high vacuum for 1 hour and then dissolved in 100 ml of dry 1,2-dichloroethane.

2.7 g of 2-benzoyloxymethyl-5-ethoxy-1,3-oxathiolane (XIII) was dried twice in a 500 ml flask by evaporation with 50 ml of benzene and then dissolved in 200 ml of dry 1,2-dichloroethane.

The silicified 6-chloropurine solution was then transferred into the 1,3-oxathiolane solution using a syringe under an argon atmosphere. 11 ml of 1M TMS-triflate (trimethyl-silyl trifluoromethane sulfonate) was added to the reaction flask. The mixture was heated at reflux for 5 hours, then cooled to room temperature. The mixture was poured into 300 ml of saturated aqueous solution of sodium bicarbonate (NaHCO3) with stirring. The organic layer was collected and the aqueous phase was extracted with CH2Cl2, (2 x 100 ml). The combined organic phase was washed with water, then dried over MgSO4, filtered and evaporated under reduced pressure. The residue was purified and separated on silica gel using hexane-ethyl acetate as eluent. 1.05 g (28%) of the less polar product, which was identified as the alpha- or trans-isomer as a foam, and 710 mg of the lower product as the beta- or cis-isomer are obtained. Total contribution 46.1%; cis:trans ratio is 1:1.4. Trans-isomer (alpha-isomer) : Rf: 0.43 in hexane:EtOAc 1:1

U.V.: (MeOH) Lambda max: 264.7 nm 1H-NMR (CDCl3):

8.76 (s, 1H, C8'-h)

8.48 (s, 1H, C2'-H)

8.06 (m, 2H, aromatic)

7.56 (m, 1H, aromatic)

7.45 (m, 2H, aromatic)

6.90 (dd, 1H, C5-H, J = 5.0 Hz)

5.78 (dd, 1H, C2-H, J = 6.0 Hz)

4.56 (m, 2H, C2-CH2OCOC6H5)

3.74 (m, 2H, C4-H)

Cis-isomer (beta-isomer): Rf 0.35 in hexane:EtoOAc 1:1

U.V.: (MeOH) Lambda max 264.7 nm

1H-NMR (CDCl3):

8.72 (s, 1H, C8'-H)

8.51 (m, 2H, C2-H)

8.00 (m, 2H, aromatic)

7.56 (m, 1H, aromatic)

7.44 (m, 2H aromatic)

6.61 (t, 1H, C5-H, J = 4.7 Hz)

5.62 (t, 1H, C2-H, J = 4.9 Hz)

4.69 (m, 2H, C2-CH2OCOC6H5)

3.66 (m, 2H, C4-H)

Example 12

Cis-2-hydroxymethyl-5-(6'-hydroxypurin-N-9'-yl)-1,3-oxathiolane (inosine derivative)

[image]

533 mg of cis-2-benzoyloxymethyl-5-(6-hyoronurin-N-9 ▪-yl)-1,3oxathiolane was dissolved in 25 ml of methanol, 5 g of sodium hydroxide (NaOH) and 3 ml of water were added to the solution. The mixture was heated for 5 hours at reflux and cooled to room temperature. The solution was diluted with 100 ml of water, neutralized with pyridine resin and filtered. The rest of the resin was washed with 100 ml of methanol. The combined filtrate was evaporated under reduced pressure. The residue was purified on silica gel using CH2Cl2 :MeOH 4 :1 as eluent. 183 mg (51 %) of the pure product was obtained which was identified as an inosine derivative) m.p. . 208-210°C; Rf 0.27 in EtOAc :MeOH 4:1

UV: ( MeOH ) Lambda max : 246 nm 1H-NMR: δ (ppm in DMSO-d6)

12.42 (s, 1H, -NH, D2O exchange)

8.36 (s, 1H, C8'-H)

8.07 (s, 1H, C2-H)

6.37 (t, 1H, C5-H, J = 5.1 Hz)

5.29 (t, 1H, -OH, J = 6.0 Hz, D2O exchange)

5.24 (t, 1H, C2-H, J = 4.9 Hz)

3.63 (m, 4H, 2H from C4-H and 2H from CH2-OH)

Example 13

Cis- and trans-benzoyloxymethyl-5-(uracil-N-1'-yl)-1,3-oxathiolanes

[image]

760 mg of uracil was heated at reflux in 30 ml of HMDS in the presence of 50 mg of (NH 4 ) 2 5 O 4 until the solution became clear. The mixture was evaporated under reduced pressure. The residue was dried under high vacuum for 1 hour and dissolved in 100 ml of dry 1,2-dichloroethane.

1.5 g of 2-benzoyloxymethyl-5-ethoxy-1,3-oxathiolane: was dried by evaporation twice with 50 ml of benzene in a 500 ml flask and was dissolved in 150 ml of dry 1,2-dichloroethane.

The silionic uracil solution was transferred to the oxathiolane solution using a syringe under an argon atmosphere and 1.5 ml of TMS-Triflate in 20 ml of 1,2-dichloroethane was added. The reaction mixture was heated at reflux under an argon atmosphere for 48 hours, cooled to room temperature and poured into 300 ml of saturated aqueous NaHCO3 solution. The organic layer was collected. The aqueous phase was extracted twice with CH2Cl2 (2 x 100 ml). The combined organic layer was washed with water (2 x 200 ml), then with one NaCl solution (1 x 150 ml) and dried over MgSO4. After filtration, the solution was removed by evaporation in vacuo and the residue was purified on silica gel using hexane:EtOAc 1:1 as eluent. 594 mg (32%) of pure product was obtained. The product appeared only as a single spot in TLC. However, the 1H-NMR spectrum indicates the presence of two cis:trans isomers in the ratio 1:1.2, which are not separated at this stage.

R12f: 0.35 in hexane:EtOAc 3:7 U.V.. (MeOH) Lambda max: 261 nm 1H-NMR δ (ppm in CDCl3)

8.88 (broad s, 1H, N3'-H)

8.05 (m, 2H, aromatic)

7.71 (d, 1H, C6'-h, cis J = 8.2 Hz)

7.57 (m, 1H, aromatic)

7.45 (m, 3H, aromatic and N3'-H)

6.55 (dd, 1H, C5-H trans, J = 2.4 and 5.4 Hz)

6.35 (dd, 1H, C5-H cis, J = 4.1 and 5.6 Hz)

5.79 (t, 1H, C2-H trans, J - 5.4 Hz)

5.73 (d, 1H, C5'-H, J =8.2 Hz)

5.57 (d, 1H, C5'-H, J = 8.2 Hz)

5.46 (t, 1H, C2-H cis, J = 3.9 Hz)

4.73 (d, 2H, -CH2O-COC6H5)

4.45 (t, 2H, -CH2O-COC6H5)

3.57 (m, 1H, C4-H)

3.17 (m, 1H, C4-H)

Example 14

Cis-2-hydroxymethyl-5-(uracil-N-1'-yl)-1,3-oxathiolane

[image]

300 mg of a mixture of cis- and trans-2-benzoyloxymethyl-5-(uracil-N-1'-yl)-1,3-oxathiolane was dissolved in 75 ml of methanolic ammonia. The mixture was stirred overnight at room temperature. The solution was evaporated to dryness. The residue was purified and both isomers were separated on silica gel using EtOAc:MeOH 98:2 as eluent.

The above product was isolated as a solid and identified as the cis-isomer.

Cis-isomer: m.p. 162-164°C; Rf 0.57 in EtoAc:MeOH 95:5

U.V.: (MeOH) Lambda max: 261.4 nm

1H-NMR δ (ppm in CDCl3):

11.36 (s, 1H, N3'-H)

7.88 (d, 1H, C6'-H, J= 8.1 Hz)

6.18 (t, 1H, C5-H; J = 4.8 Hz)

5.62 (d, 1H, C5-H; J = 8.1 Hz)

5.33 (t, 1H, C5-H; J = 5.7 Hz)

5.17 (t, 1H, -OH, D2O change)

3.72 (t, 2H, C2CH2OH, J = 4.6 Hz)

3.41 (dd, 1H, C4-H), J = 5.7 and 12 Hz)

3.20 (dd, 1H, C4-H), J = 4.6 and 9.9 Hz)

Example 15

Cis- and trans-2-benzoyloxymethyl-5-(thymin-N-1'-yl)-1 3-oxathiolanes

[image]

1.7 g of thymine was heated at reflux in 5 ml of HMDS containing 50 mg of (NH 4 ) 2 SO 4 until the solution became clear. The mixture was evaporated under reduced pressure. The residue was dried under high vacuum for 1 hour and dissolved in 150 ml of 1,2-dichloroethane.

3g of 2-benzoyloxymethyl-5-ethoxy-1,3-oxathiolane was dried by evaporation twice with 75 ml of benzene and was dissolved in 150 ml of dry 1,2-dichloroethane.

A solution of silylated thymine was transferred to the oxathiolane using a syringe under a nitrogen atmosphere. 3.3 ml of TMS-Triflate (trimethylsilyl triflate) in 30 ml of dry 1, 2-dichloroethane was introduced into the reaction mixture using a syringe under an argon atmosphere. The solution was heated at reflux under an argon atmosphere for 36 hours, cooled to room temperature and poured into 300 ml of saturated aqueous NaHCO3 solution. The organic layer was collected and the aqueous phase was extracted twice with methylene chloride (2 x 100 ml). The combined organic phase was washed twice with water (2 x 200 ml) and once with NaCl solution (1 x 150 ml) and then dried over MgSO 4 . The solution was filtered. The filtrate was evaporated in vacuo. The residue was purified on silica gel using hexane:EtOAc 1:1 as eluant. 1.3 g (35%) of pure product was obtained.

The product is shown as only one spot on TLC but the 1H NMR spectrum indicates the presence of two isomers cis and trans in the ratio 1:1.2.

Rf 0.3U in hexane:EtOAc 2:3

U.V.. (MeOH) Lambda max: 266 nm 1H-NMR δ (ppm in CDCl3);

8.60 (broad singlet, N3'-H)

8.06 (m, 2H, aromatic)

7.59 (m, 1H, aromatic)

7.49 (m, 2H, aromatic)

7.38 (d, 1H, C6'-H-cis, J = 1.3 Hz)

7.28 (d, 1H, C6'-H-trans, J = 1.3 Hz)

6.55 (dd, 1H, C5-H - trans isomer, J = 3.1 and 5.6 Hz)

6.38 (t, 1H, C5-H, cis isomer, J = 5.5 Hz)

5.78 (dd, 1H, C2-H-trans, J - 4.4 and 6.4 Hz)

5.46 (t, 1H, C2-H -cis isomer, J = 4.3 Hz)

4.69 (d, 2H, C2-CH2OCOC6H5, J - 4.2 Hz)

4.45 (m, 2H, C2-CH2OCOC6H5)

3.58 (m, 1H, C4-H)

3.13 (m, 1H, C4-H)

1.93 (d, 2H, C5'-CH3 -trans isomer, J = 1.2 Hz)

1.78 (d, 2H, C5'-CH2 -cis isomers, J = 1.2 Hz)

Example 16

Cis-2-hydroxymethyl-5-(thymin-N-1'-yl)-1,3-oxathiolanes

[image]

500 mg of a mixture of cis and trans-2-benzoylmethyl-5-(thymin-N-1'yl) 1,3-oxathiolane (XXIV) was dissolved in 100 ml of saturated methanolic ammonia. The mixture was stirred overnight at room temperature (18 hours). The mixture was then evaporated to dryness under reduced pressure. The residue was separated on silica gel using EtOAc:MeOH 98:2 as eluant.

The less polar product was identified as the cis-isomer mp: 167-168°C Rf: 0.66 in EtOAc:MeOH 95:5

U.V.. (meOH) Lambda max: 266 nm

1H-NMR δ (ppm in DMSO-d6)

11.38 (s, 1H, N3'-H)

7.73 (d, 1H, C6'-H, J = 1.1 Hz)

6.16 (t, 1H, C5-H, J = 5.5 Hz)

5.31 (t, 1H, C2-H, J = 5.9 Hz)

5.14 (t, 1H, OH, D2O change)

3.70 (t, 2H, C2-CH2OH, J = 5.1 Hz)

3.36 (dd, 1H, C4-H, J = 5.7 and 1.7 Hz)

3.16 (dd, 1H, C4-H, J = 5.5 and 11.7 Hz)

1.75 (d, 3H, C5'-CH3, J = 1.7 Hz)

Example 17

Tablet formulations

A. The following formulation was obtained by wet granulating the ingredients with a solution of povidone in water, drying and sieving, and then adding magnesium stearate and pressing.

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B. The following formulation was obtained by direct pressing; lactose is of the direct compressible type.

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C. (Controlled release formulation)

The formulation was obtained by wet granulation of the ingredients (below) with a solution of povidone in water, drying and sieving and then adding magnesium searate and pressing.

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Example 18

Capsule formulation

The capsule formulation is obtained by mixing the ingredients below and filling two-part hard gelatin capsules.

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Example 19

Formulation of injections

Active ingredient 0.200 mg Sodium hydroxide solution 0.1 M at a pH of 11. Sterile water up to 10 ml.

The active ingredient is suspended in a little water (which can be heated) and the pH is adjusted to about 11 with sodium hydroxide solution. The mass is then adjusted to the appropriate volume and filtered through a sterile membrane filter into sterile 10 ml containers that are sealed with sterile closures and closure holders.

Example 20

Suppositories

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A fifth of the solid fat is melted in a pan with a water vapor envelope at a maximum of 45°C. The active ingredient was sieved through a 200 μm sieve and added to the dissolved base with stirring, using a high-speed mixer until a homogeneous dispersion was obtained. Keeping the mixture at 45°C, the rest of the solid fat suspension was added and this was mixed to obtain a homogeneous mixture. The entire suspension was passed through a 250 μm stainless steel sieve with continuous stirring and left at 40°C. At a temperature of 38 to 40°C, 2.02 g of the mixture is introduced into suitable molds of 2 ml. The suppositories were allowed to cool to room temperature.

Example 21

Antivirus activity

In vitro testing was performed on several compounds of this invention to determine their inhibitory properties.

The results are shown in Tables 1 and 2. The concentrations shown are g/ml in incubation media that affect the sensitivity of a continuous series of T-cells developed by Dr. at the Lady Davis Institute for Medical Research (Montreal). Mark A. Wainberg upon HIV-1 infection following a protocol similar to that of H. Mitstye and S. Broder "Inhibition of in vitro infectivity and cytopathic effect of human T-lymphotropic virus type III/lymphadenopathy associated virus (HTLV-III/LAV) with 2' 3'-dideoxynucleoids", Proc. Natl. Acad. Sci. USA, 83, pp. 1911-15 (1986). Protection of the cell line from infection was monitored by staining with monoclonal antibodies against viral proteins in a standard manner (Table 1). In all experiments, comparisons were made with the AZT drug as a control. To confirm the results, the effects of the drugs were monitored by measuring reverse transcriptase (RT) activity in the U-937 line of human monocytic cells as assayed in the usual way with tritiated thymidine triphosphate (TTP) (Table 2).

Toxicity

No toxic effects were observed in the above experiments.

Table 1

Inhibition of HIV-1 product by compounds of formula (I) in MT-4 cells

a) Calculation of surviving cells (6 days in culture) using 2 g/ml compound

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b) P-24 immunofluorescence

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c) Reverse transcriptase test

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Table 2

Inhibition of HIV with compounds of formula (I) in H-9 cells

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Claims (12)

1. Process for preparing the compound of formula (1) [image] where R 1 is hydrogen; R 2 is a purine or pyrimidine base or an analog or derivative thereof; Z is S, S=O or SO2; and its pharmaceutically acceptable derivatives, which contains: a) reaction of the compound of formula (VIII) [image] where R 1 is hydrogen or a hydroxyl protecting group and L is a displaceable atom or group with a base of the R 2 -H group; (b) base interconversion of one compound of formula (I) into another compound of formula (I); (c) reaction of a compound of formula (IX) with a compound of formula (X) [image] where P is a protecting group; or (d) conversion of the compound of formula (XII) [image] into the compound of formula (1), and if necessary or desired, subjecting the resulting compound from any of steps (a) to (d) to one or two further reactions comprising: (i) removal of any protecting group; (ii) converting the compound of formula (1) or its salt into a pharmaceutically acceptable salt thereof. 2. The method according to claim 1, characterized in that the compound of formula (1) is obtained in the form of the cis isomer. 3. The method according to claim 1 or claim 2, characterized in that Z represents S. 4. The method according to any one of claims 1 to 3, characterized in that R2 is: [image] [image] where is: R3 selected from the group consisting of hydrogen, trifluoromethyl or saturated or unsaturated C1-6 alkyl group; R 4 and R 5 are independently selected from the group consisting of hydrogen, hydroxymethyl, trifluoromethyl, substituted or unsubstituted, saturated or unsaturated C 1-6 alkyl, bromine, chlorine, fluorine or iodine; R 6 is selected from the group consisting of hydrogen, cyano, carboxy, ethoxycarbonyl, carbamoyl, or thiacarbamoyl; X and Y are independently selected from the group consisting of hydrogen, bromine, chlorine, fluorine, iodine, amino or hydroxyl. 5. The process according to any one of claims 1 to 3, wherein R2 is: [image] wherein R3 is selected from the group consisting of hydrogen, trifluoromethyl or saturated or unsaturated C1-6 alkyl and R4 is selected from the group consisting of hydrogen, hydroxymethyl, trifluoromethyl, substituted or unsubstituted, saturated or unsaturated C1-6 alkyl groups, bromine, chlorine, fluorine or iodine. 6. The method according to any one of claims 1 to 5, characterized in that the compound of formula (1) is selected from: Cis-2-hydroxymethyl-5-(cytosin-1'-yl)-1,3-oxathiolane, trans-2-hydroxymethyl-5-(cytosin-1'-yl)-1,3-oxathiolane and their mixtures; Cis-2-benzoyloxymethyl-5-(cytosin-1'-yl)-1,3-oxathiolane, trans-2-benzoyloxymethyl-5-(cytosin-1'-yl)-1,3- oxathiolanon, i their mixtures; Cis-2-hydroxymethyl-5-(N4'-acetyl-cytosin-1'-yl)-1, 3-oxathiolane, trans-2-hydroxymethyl-5-(N4'-acetyl-cytosin-1'-yl)-1 ,3-oxathiolane, and their mixtures; Cis-2-benzoyloxymethyl-5-(N4'-acetyl-cytosin-1'-yl)-1,3oxathiolane, trans-2-benzoyloxymethyl-5-(N4'-acetyl-cytosin- 1'yl)-1,3-oxathiolane, and their mixtures; and Cis-2-hydroxymethyl-5-(cytosin-1'-yl)-3-oxo-1,3-oxaty-olane; Cis-2-hydroxymethyl-5-(N-dimethylamino-methylene-cytosin-1'-yl)-1,3-oxathiolane; Bis-Cis-2-succinyloxymethyl-5-(cytosin-1'-yl)-1,3-oxa-thiolane; Cis-2-benzoyloxymethyl-5-(6'-chloropurin-N-9'-yl)-1,3-oxathiolane; trans-2-benzoyloxymethyl-5-(6'-chloropurine-N-9'- il) 1,3-oxathiolane, and their mixtures; Cis-2-hydroxymethyl-5-(6'-hydroxypurin-N-9'-yl)-1,3-oxathiolane; Cis-2-benzoyloxymethyl-5-(uracil-N-1'-yl)-1,3-oxathiolane, trans-2-benzoyloxymethyl-5-(uracil-N-1'-yl)-1,3- oxathiolane, and their mixtures; Cis-2-hydroxymethyl-5-(uracil-N-1'-yl)-1,3-oxathiolane; Cis-2-benzoyloxymethyl-5-(thymin-N-1'-yl)-1,3- oxathiolane, trans-2-benzoyloxymethyl-5-(thymin-N-1'-yl)-1,3-oxathiolane, and their mixtures; Cis-2-hydroxymethyl-5-(thymin-N-1'-yl)-1,3-oxathiolane; and their pharmaceutically acceptable derivatives in the form racemic mixtures or special enantiomers. 7. The method according to any one of claims 1 to 5, characterized in that the compound of formula (1) is Cis-2-hydroxymethyl-5-(cytosin-1'-yl)-1,3-oxathiolane, and its pharmaceutically acceptable derivatives . 8. The method according to any one of claims 1 to 7, characterized in that the compound of formula (1) is obtained in the form of a racemic mixture. 9. The method according to any one of claims 1 to 7, characterized in that the compound of formula (1) is obtained in the form of one enantiomer. 10. The method according to any one of claims 1 to 9, characterized in that in step (a) the group L is selected from the group consisting of alkoxy carbonyl, iodine, bromine, chlorine or -OR, where R is substituted or unsubstituted, a saturated or unsaturated alkyl group or R is a substituted or unsubstituted aliphatic or aromatic acyl group. 11. The method according to any one of claims 1 to 10, characterized in that in step (a) the compound of formula (VIII) reacts with a silylated purine or pyrimidine base in a suitable solvent in the presence of Lewis acid or trimethylsilyl triphthalate. 12. A process for obtaining a pharmaceutical preparation, characterized in that it comprises mixing the compound of formula (1) as defined in claim 1 or its pharmaceutically acceptable derivative with a pharmaceutically acceptable carrier.